Froth flotation of oxide iron ore



Patented mi 1 1 1m 1 morn nomnonor oxmsmon one 1 a Fred DlDe Vaney, liibbing,Minnanssignorlto Erie Mining Company, Hibbing,.Minn.,- a cor- IP 9t esota it em, sto t le-art or new? lady-concerned-withithepre-treatnientand conditioning of; such pulps when using fatty acids,fatty acids soaps,-ta l loel, talloelsoapsor resinates asanionicallyiactingjcollectors. 'f'

In essence,'f-the-proce ss' of the present invention comprise'sflthefollowing combination or procedural featuresl and,operative-stepsg Thepulp is 'cleslimed and given-an acid'wash (1) to cleannparticlesljromaqueous'pulps.- thereoifteontaining also silicious gangueparticles, The'proce'ss :ofthejpresent inventionis particu Nqn 'awins.'ApplicationJanuai-y'z,1946,

SerialNo."638,707 P i 5 came. (01. 209-166) 'ferred up n the deslime'dacting collectors 'with the silicious oxidic iron pulps with which 'thepresent invention is concerned. Thus, I have found, in working withal-rkali resinate collector s, that if the pH of the circuit be droppedbelow 8.-2 through addition V thereto of an acid,the resinate collectortends to the surfaces of the dxidic iron particles whereby to enhancetheirjfloatability and simultaneously (2) to remove ironslimes from thesurface of the silicate minerals whereby to depress the float-- ability0? the latter; To :eflectthe acid wash, the pulp is thoroughlyadmixedwith a suitable acid, usually a-mineral'acid, in an amount equivalenttomore than 1 but not moreathan about 3 pounds'of concentrated sulphuricacid per ton of the pulp, dry-basis. The acid-washed pulp is thenrepulpedwith fresh water, and then thickened to a solids content of atleast 65% and desirablybetween 65% and 80%. The pulp, at

high pulp density, is made mild y yet definitely alkaline by theincorporation thereinto of a suitable alkali, e. g., caustic soda orsodaash, in an amount sufllcient to give the pulp a pH of from 8.0 to 8.5,e. g.,' about 8.2, depending to some extent upon the identity of thecollector. Thereupon, the mildly alkaline pulp is conditioned withbreakdown to tree resin and an alkali metal salt of, theadded acid (e.g., sodium'sulphate); in such case, the resin continues .to function asan amonically acting collector but in a manner much i less efieotivethan the solubleres'inate- When efiective'compounds an emulsion of theselected anionically acting r agent,e. g., a materially alkaline andquite soluble sodium'resinate soap ora talloel soap, and a suitable oil,e. g., fuel oil. The so-conditioned pulp is ready to be diluted withwater to 20-25% solids and subjected to; froth flotation in conventionalmanner.- I

In the cases o f,certain ores it is'advantageous to first deslimeandthen acid wash. With other ores it issimpler to acid wash first and thendeslime. Thesetwooperations are interchangeable and the choice; dependson the character of the ore, the type of mill water being used, thesoluble salts encountered, etc.

I have found that the degree of alkalinity contors.

working with alkali metal soapsof talloel (which latter consistsessentially of'fatty acids and resin acids in approximatelyequalamounts) much the same result attends lowering thepH of the pulpcircuit as in-thecaseof. the soluble'resinates.

Thepetroleum hydrocarbon'sulphonates, such for example as the -wellknownmahogany soaps, behave just oppositely they-arei'quites soluble inacidic solutions, but break down to fiotatively inalkaline. 1

The above experimentally derived facts pertain to the efiect of too lowa pH value when. working with the above named anionically acting collecfI have found, on the other hand, that too great anflalkalinity of.the.pu lp circuit is equally as disadvantageous as too low a value.Thus, numerous experiments have established that as'the alkalinity isincreased above, pH 8.5 l the grade of the resulting concentratedepreciates and at a pH of approximately 9.5 the separation tends to bereversedi. e., tends so to operate as j v to float the siliciousparticles in'preferencerto the oxidic iron particles.

Table No. 1 immediately following shows the effect of varying the pH ontheianionic flotation sota. I

l and acid-washed -pulpu'. prior 'to'conditioning with the aforesaidagents of rea im n e t the? ub e ento i- 1 tioning and. flotation-L -Theabove referred 'to'; mild alkalinity" is essential to' 'good fiotationresults when usingthe above-named; anionically when the pulp circuit ismade Table #L-Eflect of varying m on iron ore sion as collector my, PerCent t pH Flota- Per Cent m Tm tion Pulp Produc Wt. r

Iron Silica Composite 100. 00 14. 94 100. 00

#197 8. 0 Ciiliceili:l'8te. 19. 09 61. 97 0. 66 83. 31 Midd1ing 5. 14 887. 11 Tailing 75. 77 1 79 9. 58

Composite. 100. 00 l4. 1!) 100. 00

#206 8 3 Concentrate. 20. 84 53. 57 i8. 94 79. 21 iddling 20. 71 6. 8310.00 Tailing 58. 45 2. 60 10. 79

Composite 100. 00 14. 09 100. 8

#207 9 5 Concentrate 01. 13 14. 71 72. 45 61.96 Middling. 13. 2o 11. 2710. 27

Talllngn 67 15. 69 27.

' Composite 100.00 14. 51 100. 00

Deslimed Head Sample. 14. 53

Tm comlitions.-Ore given acid wash using 3 lbs. msomon ore and deslimcd.Orc

regulped with fresh water. or

Conditioned at high solids with acid or caustic to give an It will benoticed that optimum results were poor that not enough concentrate wasfloated to secured at a pH of 8.0-test #197. With a lower pH, as intests #209 and #213, while a good concentrate was produced the tailingsundesirably increased in grade-apparently because the warrant having theproducts analyzed. At a. pH of 9.2 the selectivity was poor, as it waswith the other two collectors in circuits as alkaline as pH 9.0.

Table #2.Eflect of varying pH on iron ore flotation using talloel-jueloil as collector A'ssay,Pcr Cent er Cent Test zg g Product Per CentTotal p wt. 1

Iron Silica mu 1. 71 No Analysis Composite 100.00

#204 8. 0 Concentrate 20. 77 60. 8. 86. 61 Middling. .5. 02 14. 79 5. i1'lailing 74. 21 1. 62 8. 28

Composite 100. 00 14. 49 100. 00

Composite 100. 00 14. 34 100. 00

Dcslimcd Head Sample. 14. 53

as such, separately, and conditioned at high solids.

In each of above tests 2 lbs.

tallocl and 2 lbs. fuel oil per ton of dcslimcd ore usedas collector.

sodium resinate collector broke down to a resin under the acidicconditions maintained. It will be observed, on the other hand, that asthe alkalinity is increased beyond pH 8.0 or 8.2-as in tests #206 and#207-the grade of concentrates drops off until at pH 9.5 the separationis reversed and more silica than iron is floated.

The beneficial efiects of using a mildly alkaline circuit are notlimited'to the resinates but apply also to alkali metal soaps oftalloel.

Table #2 shows the results using tallcel as a collector.

The conditions of test #204 sav optimum separation results.

It was found that alkali metal soap of talloel could be substituted forthe talloel of the above experiments with comparable results.

In Table #3, following, are assembled data pertaining to the flotationoi oxidic iron from a deslimed, acid-washed and then alkalized pulp ofan oxidized taconite ore material, using an aqueous emulsion of sodiumresinate collector In an acid pulp the results were so 18 and fuel oil.I

Table #3 on flotation tests using oxidized Taconite, pool mine sodiumresinate-fuel oil emulsion as collector Test conditions.-Sample ofoxidized Taconite crushed and wet ground to 100 mesh. Deslimed.Conditioned with 3 lbs. H:S|/ton deslimed ore. Repigliped with freshwater. Conditioned at 75% solids with 0.3 lb. s mm hydroxide per tonfeed and an emulsion made up of %sodium resinate, 10% fuel oil and 80%water. Amount of collector used was equivalent to 2 lbs. of resinate and2 lbs. of fuel oil per ton of deslimed feed.

From a series of experiments I have found that best results followholding the pH at from 8.0 to 9.0 at the point where the collector isadded to the thickened pulp, the upper limit being carefully controlledto eliminate activation of the silica, while in the rougher cells the pHpreferably is maintained at 7.8-8.5 and in the cleaner cells at 7.0-8.5.The data indicate that it is helpful to make the pulp nearly neutralduring the cleaning step, as the silica particles then sink from therougher froth better and a cleaner concentrate is secured.

An advantage of the present method is that by controlling the pH one caneflect an excellent separation by the use of relatively small amounts ofresinates and talloel soaps, which are cheaper than sulfonates. Bykeeping the circuit alkaline one secures full use of the collector(resinate. or talloel soap) and requires only half as much as in an acidcircuit. The flotation separation is carried on in alkaline circuitwhich is not corrosive to iron and steel equipment as an acid circuitwould be.

I claim:

1. Process of concentrating by anionic froth floatation the oxide ironof pulps of oxidic ironbearing ores and ore-like materials includingtaconites containing silicious gangue, which comprises treating the pulpwith a mineral acid of a strength and in an amount sufllcient to cleanthe sulfaces of the pulp particles, desliming the pulp, treating thedeslimed acid-treated pulp at a pulp density at least equivalent to 65%solids with an alkaline-acting alkali metal compound in an amountsuflicient to raise the pH of the pulp to from 8.0 to 9.0, conditioningthe alkalized pulp with a reagent charge consisting essentially of anaqueous dispersion of an anionically acting agent of the groupconsisting of alkali metal soaps of talloel and alkali metal resinatesand an oily carrier, diluting the so-conditioned pulp with water, andsubjecting the diluted conditioned pulp to froth flotation.

2. Process of concentrating by. anionic froth flotation the oxidic ironof pulpsuif oxidic ironbearing ores and ore-like materials includinstaconites containing silicious gangue, which comprises treating the pulpwith a mineral acid of a strength and in an amount equivalent to from 1pound to 3 pounds of concentrated sulphuric acid per ton of the pulpsolids and sumcient to clean the surfaces of the pulp particles,desliming the pulp and repulping in fresh water, treating the deslimedacid-treated pulp at a pulp density at least equivalent to 65% solidswith an alkaline-acting metal compound in an amount sufllcient to raisethe pH of the pulp to from reagent charge consisting essentially of anaqueous emulsion of an anionically acting agent of the group consistingof alkali metal soaps of talloel and alkali metal resinates and an oilycarrier, diluting the so-conditioned pulp with water, and subjecting thediluted conditioned pulp to froth flotation.

3. Process of concentrating by anionic froth flotation the oxidic ironof pulps of oxidic ironbearing ores and ore-like materials includingtaconites containing silicious gangue, which comprises treating the pulpwith a mineral acid of a strength and in an amount sufficient to cleanthe surfaces of the pulp particles, desliming the pulp, treating thedeslimed acid-treated pulp at a pulp density at least equivalent tosolids with an alkaline-acting alkali metal compound in an amountsufficient to raise the pH of the pulp to from 8.0 to 8.5, conditioningthe alkalized pulp with a reagent charge consisting essentially of anaqueous emulsion of an anionically acting alkali metal resinate and anoily carrier, diluting the so-conditioned pulp with water, andsubjecting the diluted conditioned pulp to froth flotation.

4. Process of concentrating by anionic froth flotation the oxidic ironof pulps of oxidic ironbearing ores and ore-like materials includingtaconites containing silicious gangue, which comprises treating the pulpwith a mineral acid of a strength and in an amount suificient to cleanthe surfaces of the pulp particles,-desliming the pulp, treating thedeslimed acid-treated pulp at a pulp density at least equivalent to 65%solids with an alkaline-acting alkali metal compound in an amountsufficient to raise the pH of the pulp to from 8.0 to 8.5, conditioningthe alkalized pulp with a reagent charge consisting essentially of anaqueous emulsion of an anionically acting sodium resinate and an oilycarrier, diluting the so-conditioned pulp with water, and subjecting thediluted conditioned pulp to froth flotation.

5. Process of concentrating by anionic froth flotation the oxidic ironof pulps of oxidic ironbearing ores and ore-like materials includingtaconites containing silicious gangue, which comprises treating the pulpwith a mineral acid of a strength and in an amount sufllcient to cleanthe surfaces of the pulp particles. desliming the pulp, treating thedeslimed acid-treated pulp at a pulp density at least equivalent to 65%solids with an alkaline-acting alkali metal compound in an amountsumcient to raise the pH of the pulp to from 8.0 to 9.0, conditioningthe -alkalized pulp with a reagent charge consisting essentially of anaqueous emulsion of an anionically acting sodium soap of talloel and anoily carrier, diluting the so-conditioned pulp with water, andsubjecting the diluted conditioned pulp to froth flotation.

' FRED D. Dn VANEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,305,502 Booth Dec. 5, 19422,885,054 Booth Sept. 18, 1945 2,410,876 Booth Oct. 29, 1946 2,410,377Booth -1 Oct. 29, 1946 OTHER REFERENCES Milling Methods 1939, publishedby American Institute of Mining, J Metallurgical Engineers,

